Protein

The diagram shows a biological molecule found in cells.

Which arrow labels a peptide bond?

• A

• B

• C

• D

Tags

NGSS.HS-LS1-6

The tertiary structure of a protein molecule is maintained by which bonds?

• A

• B

• C

• D

The protein myoglobin has a similar function to haemoglobin except myoglobin does not have a quaternary structure.

Why does myoglobin not have a quaternary structure?

• Myoglobin has only one polypeptide chain.

• Myoglobin has a fibrous rather than a globular structure.

• Myoglobin does not contain a haem group.

• Myoglobin does not contain any alpha helices.

How can the quaternary structure of haemoglobin be described?

1)     A specific order of amino acids

2)     A globular structure

3)     An α-helix

4)     A dipeptide

5)     Four polypeptide chains connected together

• 5) only

• 2, 3 and 5

• 1, 2, and 3

• 2 and 5

Which description of collagen is correct?

• Three collagen fibril coil around each other to form a strong, insoluble structure termed a triple helix

• Both amino acids of the same polypeptide and amino acids of different polypeptides are joined by peptide bonds.

• The smallest amino acid, glycine, is found in a high proportion in collagen.

• Collagen polypeptides consist of many alpha helices in a regular spiral arrangement.

In protein molecules, which bonds are responsible for producing the primary, secondary and tertiary structure?

• A

• B

• C

• D

Two amino acids, both containing two carboxylic acid (-COOH) groups are illustrated below.

Which labelled groups take part in the formation of a dipeptide of these amino acids?

• 1 and 5

• 2 and 3

• 2 and 4

• 1 and 4

Tags

NGSS.HS-LS1-6

The protein haemoglobin contains iron.

What is the role of iron within the molecule?

• It undergoes reduction and oxidation (redox) reactions.

• It stabilizes the quaternary structure of haemoglobin.

• It enables haemoglobin to dissolve in red blood cells.  

• It binds oxygen to haemoglobin.

Protein molecules contain multiple different types of bond, some of which are stronger that others.

Which is the correct order from weakest to strongest?

• Disulfide bonds, ionic bonds, hydrogen bonds, hydrophobic interaction.

• Ionic bonds, disulfide bonds, hydrophobic interactions, peptide bonds.  

• Hydrophobic interactions, hydrogen bonds, peptide bonds, ionic bonds.  

• Hydrophobic interactions, hydrogen bonds, disulfide bonds, peptide bonds.

Haemoglobin carries oxygen in the blood.

Which of the following best describes why this is possible?

1)     Oxygen binds to iron reversibly

2)     Oxygen binding causes haemoglobin to change shape

3)     Oxygen binds to the haem group

• 1) only

• 1) and 2)

• 2) and 3)

• 1, 2 and 3